Drawing instrument.



No. 768,997. PATBNTED AUG. 30, 1904. E. s. JOHNSON.

DRAWING INSTRUMENT.

APPLIOATION IILED FEB. 12, 1904.

N0 MODEL.

v v W WITNESSES. INVENTOH Q Zdwz'n ,J Ja/zzwvm F I BY I I A TTOHNE Y3 draw curves.

Patented August 30, 1904.

PATENT. OFFICE.

EDWIN STANTON JOHNSON, OF LINCOLN, NEBRASKA.

DRAWING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 768,997, dated A g 30, 1904.

Application filed February 12, 1904. Serial N0.193,275. (N model.)

T0 at whom it mm "NU/013F721.

Be it known that I, EDWIN STANTON J OHN- SON, a citizen of the United States, and a resident of Lincoln, in the county of Lancaster and State of Nebraska, have invented a new and Improved Drawing Instrument, of which the following is a full, clear, and exact description.

Hy invention relates to drawing instruments used for certain special purposes to be referred to.

The objects of my invention are to provide a drawing instrument which is simple in con struction and cheap to manufacture and is capable of use for drawing ellipses and circles of various sizes.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures.

Figure 1 is a perspective view of a preferred form of my invention, showing its use for drawing an ellipse. Fig. 2 is a plan view of the same. Fig. 3 is a sectional view on the line 3 3 of Fig. 2, partly in elevation. Fig. 4 is a sectional view on the line4 4 of Fig. 2, and Fig. 5 is a sectional view on the line 5 5 of Fig. 2. 4

In the drawings, represents the body of the instrument, having attached thereto or formed integral therewith, as preferred, at the ends or in any desired position projecting points 11, of rubber or other suitable material. These projections or corrugations are designed for the purpose of preventing slipping and to do away with the present necessity of passing pointed fasteners through the paper when the instrument is used in order to The body of the instrument is also preferably provided with a long slot 12, extending from one end of the body to the other, for the purpose of receiving projections upon the two slides 13 and 14 and securing them in position.

15 is a screw passing through the slide 13 and screwing into a bottom piece 16 in such a manner as to secure the slide in any adjusted position to thebody part of the instrument,

as shown in Fig. 4. 17 'is a similar screw for holding the slide 14 in position.

Upon the slide 13 is a small projection or other device 18, perforated to hold the end of a flexible cord, string, or wire 20, the other end of the flexible connection 20 being held by a similar device 19 on the slide 14. 21 represents a pencil which is adapted to be guided by this flexible connection.

Upon the slide 14 is preferably placed a spring 22, having a bar 23 projecting into the projection 19, as shown in Fig. 5, for the purpose of holdingthe cord in position. This spring is attached to the slide 14 by means of a set-screw or similar device 24. Upon one edge of the bod y10 is formed a graduation 25, extending in opposite directions from a central zero-point.

.It will be readily observed that an instrument constructed in accordance with the principles herein set forth will be very simple, compact, and durable; that it will be capable of use for drawing ellipses of all shapes and sizes within the limits prescribed by thelength of the body-piece 10, which can be made in various sizes to suit different needs, so that it can also be used for drawing semicircles of any desired radius by the simple expedient of setting the two slides 13 and 14 in contact at their contiguous edges, which will bring the two points of attachment of the flexible con nection 20 into substantial coincidence. The flexible connection 20 is designed to be adjusted in length at the projection 19 through the instrumentality of the spring 22 and the bar 23. r

I do not wish to be limited to the exactform shown in the drawings, as many modifications may be made therein without departing from spring for normally holding said stud firmly I flexible connection, with means for fastening in contact with the connection. both of said bottom pieces to theways at any 2. In a drawing instrument having Ways, point. the combination of a pair of plates mounted 1 In testimony whereoflhave signed my name 5 above said \vaye, adapted to slide on the ways i to this specification in the presence of two suh- 5 independently of each other, and each having scribing witnesses. a detachable bottom piece adapted to slide in EIHVIN S'IVANVION JOHNSON. said ways and having means for attaching a Witnesses: flexible connection thereto, comprising a stud, WILLIAM .H. JENNINGS,

IO and [116mm for musing the stud to bear on the j LOUISE ALEXANDER. 

